1. Field of the Invention
The invention relates to a method of interconnecting first and second synchronous polyphase AC networks having respectively phase lines for regulating transfer of active power from one of said AC networks to the other of said AC networks. The invention also relates to a passive interconnecting apparatus for the same purpose.
2. Brief Description of the Related Art
Known in the art, there are U.S. Pat. Nos. 4,983,856 (PELLETIER) and 4,621,198 (ROBERGE et al.); and N. G. Hingorani, "Flexible AC Transmission Systems (FACTS)-Overview", Panel Session on FACTS, IEEE Winter Power Meeting, Atlanta, 1990; L. Gyugyi, "Solid-State Control of AC transmission", Panel Session on FACTS, IEEE Winter Power Meeting, Atlanta, 1990; R. M. Maliszewski et al, "Power Flow Control in a Highly Integrated Transmission Network", CIGRE 1990 session 37-303; C. A. Falcone, "Electric Utility Industry Structure in the United States", IEEE Power Engineering Review, April 1992; E. V. Larsen, "Control aspects of FACTS applications", EPRI Workshop on FACTS, the future in High-Voltage Transmission, Nov. 14-16, 1990; and W. A. Mittelstadt, "Considerations in planning use of FACTS devices on a utility system", EPRI Workshop on FACTS, the future in High-Voltage Transmission, Nov. 14-16, 1990, which all relate to Flexible AC Transmission Systems (FACTS). FACTS most often designates thyristor-based systems characterized by static and dynamic control of the power flow and/or voltage. Over the past years, FACTS have been increasingly considered to solve power transmission problems and to manage more efficiently the energy exchanges between various partners. The main advantage of FACTS is that they can be applied to existing networks in order to achieve greater performance and can be implemented progressively. Generally, FACTS are thyristor or GTO (Gate Turn-Off) applications using sophisticated controls. They comprise static vat compensators, thyristor-controlled series capacitors, thyristor-switched phase shifters, and even generalized phase-shifter/voltage regulators. They require mechanical or electronic switches as well as a closed-loop controller in order to achieve the power control.
The purpose of these technologies is to facilitate the supply of loads in flexible and rapid fashion, while providing optimal management of electrical networks. In most cases, they allow a "controlled flow", thus removing some of the constraints of the "free flow" of power. In some cases, they are used to interconnect non-synchronous networks.
Under the current free flow mode, some problems encountered essentially involve regulating the power flow in steady state. However, certain networks may be sensitive to daily or seasonal load variations and may require additional reactive power to adjust their voltages. Other networks may require fast control of voltage and power at different points in the network in order to maintain stability.